Answer question on the basis of your understanding of the following paragraph and the related studied concepts.
A Charges placed at a point in space produces an electric field everywhere in the surrounding. When another charge is borught in the field of first charge, it experiences a force . The electric field at a point is space due to given charges is defind as the force that a unit positive charges would experience if placed at that point.
It we consider a system of charges `q_1, q-2,q_3 .....` with position vectors `oversetto (r_1 ) , oversetto (r_2) , oversetto (r_3) .....` relative to some origin O, then electric field at a point in space due to the system of charges is determined by finding the vector sum of fields due to all individual charges of the charges system.
We have a charges configuration as shown here. Without actual calculations guess the value of net electric field at a point O, the centre of the square ABCD , Give reason for your answer.
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Explanation

Net field at point O will be zero because AO =BO =CO =DO and so field of `q_1 ` will be just balanced by field due to `q_3` and field of `q_2` will be just balanced by field due to `q_4`